All liquid concrete that is still uncured needs to be contained, to hold the concrete in place until it hardens sufficiently to hold its own shape. With concrete slabs, the freshly-poured concrete may be retained by existing features such as upright walls, curbs, edgings, etc., or by some form of temporary shuttering also known as a “formwork”. The construction of formworks can be quite complicated and expensive, especially on vertical concrete structures such as vertical columns. Indeed, the cost of formworks generally represents a significant proportion of the total cost of the completed concrete structure.
Recently, the use of disposable formworks has been preferred over the use of permanent formworks made of an assembly of wooden or metal stakes, especially when forming vertical concrete structures such as upright columns. After concrete has been cast in a permanent formwork, the wooden or metal stakes cannot be removed before the concrete has at least partially solidified. Unfortunately, the concrete adheres to the stakes of the formwork once it has partially solidified, thus making the stake removal procedure a time-consuming and laborious task.
Many types of disposable formworks have been devised herein to date. For example, disposable formworks made of polystyrene (non-recyclable material) exist, but are plagued with environmental drawbacks. Indeed, when polystyrene formworks are used out in the open on a worksite, wind impinging on the formwork can cause the polystyrene to crumble into granules which eventually become scattered all over the worksite. Moreover, a polystyrene formwork becomes so deteriorated after a single usage that it cannot be used twice. Therefore, pollution occurs each time a polystyrene formwork is used since it must be discarded after a single use but cannot be recycled.
To obviate the environmental drawbacks of using polystyrene, recyclable paperboard has been used in the construction of formworks. Some paperboard formworks generally consist in a paperboard band, made of a plurality of laminated paper plies, wound helicoidally to form a cylindrical tube. The inner wall of the tube is coated with a liner of impervious material (e.g. a plastic sheet) to prevent the moisture of the concrete poured and setting up in the tube to penetrate across the paperboard and cause the delamination of its plies. Other paperboard formworks are structured from a tubular body composed of a number of assembled parts glued together at their interconnecting edges, and a band of reticulated material, e.g. fibreglass mesh, is rolled up helicoidally around the parts of the tubular body ensuring proper mechanical rigidity of the formwork.
For example, U.S. Pat. No. 6,260,816 discloses a discardable formwork for forming columns that relies on the above principles.
The above-described formworks are however still too expensive to produce and time consuming to remove.
In an attempt to improve over the prior art formworks, in US patent application No. 2006/0016150, the Applicant of the present invention provided an improved paperboard formwork that is entirely recyclable and less expensive to produce.
However, it would be still desirable to provide an improved recyclable formwork that would be easier to use and that would even lower the total cost of the completed concrete structure.
Moreover, in the field of packaging, the use of packaging boxes or assemblies specially devised for specific packaging applications has widely spread during the last years. These boxes or assemblies are generally manufactured according to specific dimensions required by a particular application, and can generally not be reused for another application.
It would therefore be desirable to provide a new packaging assembly that would be very easy to produce and use at a low cost while being at least partially reusable.